The nucleus represents a cellular control unit that regulates all events concerning the storage and processing of
DNA and RNA. It is organized by highly crowded, dynamic assemblies of proteins and nucleic acids in molecular
machines, ribonucleoprotein complexes, clusters of ongoing nuclear processes, nuclear bodies, and chromatin. This
review discusses the occurrence of nuclear protein aggregation with special emphasis on the functional architecture of the
nucleus, and quality control by the ubiquitin-proteasome system.